Storage stable liquid fugitive colored fire-retardant concentrates

ABSTRACT

This disclosure relates to fugitive color systems and storage-stable fugitive colored liquid long-term fire retardant compositions comprising a fugitive color system. The fugitive color system comprises a fugitive color pigment. In particular, disclosed herein is the identification of fugitive color pigments exhibiting hydrophilic or diminished hydrophobic tendencies. And, in certain aspects, the fugitive color pigment is fluorescent.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 62/685,654, filed Jun. 15, 2018, the entirecontents of which are hereby incorporated by reference for all relevantpurposes.

FIELD OF THE INVENTION

This disclosure relates to fugitive color systems and storage-stablefugitive colored liquid long-term fire retardant compositions comprisinga fugitive color system. The fugitive color system comprises a fugitivecolor pigment. In particular, disclosed herein is the identification offugitive color pigments exhibiting hydrophilic or diminished hydrophobictendencies. And, in certain aspects, the fugitive color pigment isfluorescent.

BACKGROUND

Long-term fire retardants used for the suppression, containment, andcontrol of wildland fire consist of an aqueous, thickened,corrosion-inhibited, ammonium phosphate solution, colored for visibilityand optionally containing other functional components. The retardantsolution is thickened with a water-soluble polymer to improveapplication characteristics and colored so that it is visible at thetime of application. Most long-term retardant solution is appliedaerially from fixed-wing aircraft or helicopters although ground tankersor engines can, and are, being used to apply it as well. The compositionand characteristics of long-term retardants currently are formulated tomeet the requirements of U.S.D.A., Forest Service Specification5100-304c, which is incorporated by reference herein in its entirety.

Long-term fire retardant solutions are most effective when applied, atan optimum application rate, dependent on fuel loading, fire intensityand weather, in front of the advancing flame front, allowing the fire topenetrate the line of retardant solution coated fuel. Retardantvisibility makes it possible to assure that the application of retardantsolution on the fuel is continuous and at a rate consistent with thefuel loading and fire intensity. When the retardant is applied at aneffective rate and over a wide enough area so that burning brands arenot blown beyond the retardant line, the flame length and rate of flamespread decreases as the flame front advances into the treated fuelallowing ground forces to better gain control of the situation.

In practice, a retardant concentrate is delivered to a fire facilitywhere it is stored and mixed or blended with water prior to actual use.In most cases the fire facility is located at an airport capable ofservicing fixed wing aircraft of the type used to transport and deliverlong-term fire retardant to an out-of-control fire. In other cases, theretardant concentrate is delivered to mobile and portable equipmentlocated near an out-of-control fire. This mobile or portable equipmentis capable of servicing either fixed wing (airplanes) or rotor-wingaircraft (helicopters) that are capable of delivering long-term fireretardant solution to the fire. As delivered to the Agency withresponsibility for wildland fire control, the retardant concentrate canbe a dry powder or a concentrated liquid. If the retardant is deliveredas a dry-powder it must be mixed with water at a prescribed weight perunit volume of water to prepare a retardant solution that issubsequently stored until pumped into a transport and/or applicationvehicle (ground tankers or engines, helicopters or fixed wing aircraft).When the fire retardant is delivered to the storage facility as aconcentrated liquid, the concentrate is transferred from the deliveryvehicle and stored without dilution. When fire retardant use iscontemplated, the liquid fire retardant concentrate is diluted withwater, at the prescribed volume per unit volume, inline during transferdirectly to the transport and application vehicle.

Tanks capable of containing either the long-term fire retardant solutionor the liquid fire retardant concentrate are maintained on site forstoring large volumes, generally thousands of gallons, of the retardantconcentrate or solution. In either case, the liquid Concentrate and theretardant solution is expected to remain homogeneous, or capable ofbeing easily and rapidly re-homogenized before discharge, dilution andapplication.

During the early 1980s, red scars left on the landscape by persistentred iron oxide pigment that was used to color wildland fire retardantsbecame an aesthetic concern. Because of this concern, fire retardantsolution was sometime not used, although desperately needed, to gaincontrol of wildland fire in scenic areas. This led to Agency request fora fugitive color pigment that was visible at the time of application andfor a few days thereafter, but then faded becoming less visible withtime. The rate of fade of a fugitive pigment is dependent on theultraviolet light intensity and duration in natural sunlight exposure.The fugitive color-pigment can be manufactured by admixing a suitablequantity of ultraviolet sensitive dye with a suitable monomer prior topolymerization. The colored polymer is then milled to a very finepowder, e.g. less than about 10-microns. The chosen dye within thetransparent polymer provides a hue that is vivid and contrasts with thenatural colors of wildland fuels sufficiently so that it is visible tothe human eye during fire retardant application on the fire during thefire prone seasons of the year. Since the red color of iron oxide wasconsidered most visible when applied within the wide range of colorscommonly found in the wildland fire environment, an Internationalorange-red was initially chosen for the fugitive pigment. The amount ofcolor pigment present in the retardant solution is relatively small,i.e., generally less than 0.5%.

Fugitive colored retardant solutions are the product of choice in areaswhere aerially delivered retardant applications remain visible to thegeneral public long after containment of the fire and, consequently,result in perceived aesthetic and environmental issues.Iron-oxide-colored retardants continue to be used in wilderness andother remote areas of the United States, Canada and other countrieswhere visual aesthetics are not presently a concern. Long-termretardants are colored so that aerial observers and ground troops canvisually tell the difference between retardant treated fuels anduntreated fuels. This is necessary to assure that gaps in retardanttreated lines or areas that would allow fire to circumvent or penetratethrough the retardant line, can be seen and can be repaired. It shouldbe noted that fire-retardant solutions can result in some discolorationafter the fugitive pigment has totally faded while opacifiers remain.This permissible level of discoloration cannot, however, be noticedvisually from a distance.

Fugitive-colored retardants are more difficult to see than iron oxidecolored retardants in some fuel types and colors. Therefore,fugitive-colored retardant solutions that are easier to see in all fueltypes are needed. In addition, the polymer surface of current fugitivecolor pigments is an organic polymer that exhibits a level ofhydrophobia, i.e., during manufacture of the fire retardant concentrate,the current fugitive pigments are very difficult to wet and homogenizewithin aqueous media. Further, the current fugitive colored pigmentstend to form a matte of considerable thickness during static storage.This matte clings to tank walls during static storage and even duringrecirculation. The matte is an indication of concentrate instability,i.e., non-homogeneity.

When a fire emergency occurs and an application vehicle is in the pit,on-site personnel immediately begin retardant concentrate discharge fromthe bottom of the storage tank through a dilution system designed toprovide the correct ratio of retardant concentrate and water anddirectly inline to the transfer and application vehicle. Generally,loading of the application vehicle is completed within 10 to 15-minutesand the vehicle is dispatched with the same haste as with any otheremergency equipment. Therefore, it is essential that the concentratedliquid be homogenous (stable) or capable of being homogenized within avery few minutes.

SUMMARY

Provided for herein is a fugitive color system comprising a fugitivepigment and a water insoluble opaque material, wherein the fugitivepigment comprises a dye encapsulated within a polymeric material. Incertain aspects, the fugitive pigment exhibits hydrophilic behavior orreduced hydrophobic properties. In certain aspects, the fugitive pigmentis hydrophilic. In certain aspects, the dye is a fluorescent dye and thefugitive pigment is a fluorescent fugitive pigment. In certain aspects,the fugitive pigment is a fluorescent magenta in color. In certainaspects, the fugitive pigment has a Lab color spacing of “L” in a rangefrom about 34 to about 89, “a” in a range from about 18 to about 83, and“b” in a range from about −61 to about 56. In certain aspects, the waterinsoluble opaque material comprises a finely divided iron oxide pigment,zinc ferrite, tri-calcium phosphate, barium phosphate, or titaniumdioxide. In certain aspects, the water insoluble opaque materialcomprises a finely divided iron oxide pigment.

In certain aspects of a fugitive color system disclosed herein, thefugitive pigment of the fugitive color system has at least one propertyselected from the list consisting of: (i) a 0.5% (w/w) suspension of thefluorescent fugitive pigment in distilled H₂O has a pH of about pH 4 topH 7 (e.g., pH about 5.6); (ii) the fugitive pigment has a softeningpoint of ≥60° C. (e.g., about 134° C.); (iii) the fugitive pigment has amelting range of ≥130° C. (e.g., about 145° C. to about 150° C.); (iv)the fugitive pigment has a particle density of about 1.2 g/ml to about1.5 g/ml (e.g., about 1.2 g/ml); (v) the fugitive pigment has anapparent bulk density of about 0.25 g/ml to about 0.37 g/ml (e.g., about0.37 g/ml); (vi) the fugitive pigment exhibits oil absorption of about55 g/100 g to about 80 g/100 g (e.g., about 80 g/100 g pigment); and(vii) the fugitive pigment has a mean particle size of about 4.5 μm toabout 5.0 μm. In certain aspects, the fugitive pigment of the fugitivecolor system has two, three, four, five, six, or seven of aboveproperties (i), (ii), (iii), (iv), (v), (vi), or (vii). In certainaspects, the fugitive pigment has a surface free energy of about 33, 35,40, 45, 48.8, 50, 55, 58.8, 60, 70, 80, 85, or 90 mN/m, or any range inbetween. In certain aspects, the fugitive pigment has a polar componentvalue of about 5, 6, 7, 8, 10, 12, 15, 20, 20.9, 25, 26.5, 30, 40, 50,or any range in between. In certain aspects, the fugitive pigment iseasy to incorporate into aqueous media. In certain aspects, the fugitivepigment incorporates more quickly into an aqueous media than a controlfugitive pigment that does not exhibit hydrophilic behavior and/or isnot hydrophilic. In certain aspects, a dry-powder component for use in aliquid fire-retardant concentrate comprises a fugitive color system andthe dry-powder component has a surface free energy of about 33, 35, 40,45, 48.8, 50, 55, 58.8, 60, 70, 80, 85, or 90 mN/m, or any range inbetween. In certain aspects, a dry-powder component for use in a liquidfire-retardant concentrate comprises a fugitive color system and thedry-powder component has a polar component value of about 5, 6, 7, 8,10, 12, 15, 20, 20.9, 25, 26.5, 30, 40, 50, or any range in between.Certain aspects provide for a dry-powder component comprising a fugitivecolor system as described herein. In certain aspects, the dry-powdercomponent is easy to incorporate into aqueous media. In certain aspects,the dry-powder incorporates more quickly into an aqueous media than acontrol dry-powder component.

Certain aspects provide or a liquid fire-retardant concentratecomprising a fugitive color system as described herein, suspended in aliquid fire-retardant component. Certain aspects provide a liquidfire-retardant concentrate comprising a dry-powder component asdescribed herein, suspended in a liquid fire-retardant component. Incertain aspects, the fugitive color system and/or dry-powder componentis in an amount of about 1.0% to about 1.5% (w/w) of the fire-retardantconcentrate. In certain aspects, the liquid fire-retardant component isselected from the group consisting of an ammonium phosphate solution, anammonium sulfate solution, an ammonium thiosulfate solution, andmixtures thereof. In certain aspects, the liquid fire-retardantcomponent is an ammonium phosphate solution. In certain aspects, theliquid fire-retardant component is a 10-34-0 agricultural fertilizersolution. In certain aspects, the liquid fire-retardant component is an11-37-0 agricultural fertilizer solution. In certain aspects, the liquidfire-retardant concentrate also comprises one or more of: a suspendingclay; a corrosion inhibiting system; or a biopolymer, suspended in theliquid fire-retardant component. In certain aspects, the fugitive colorsystem, fugitive pigment, and/or the dry-powder component is capable ofstabilizing the fire-retardant concentrate. In certain aspects, thefugitive color system, fugitive pigment, and/or the dry-powder componentstabilizes the fire-retardant concentrate. In certain aspects, thefire-retardant concentrate exhibits compositional stability throughout.In certain aspects, the fire-retardant concentrate is more stable than acontrol fire-retardant concentrate that is identical in compositionexcept for not containing a fugitive pigment exhibiting hydrophilicbehavior and/or a hydrophilic fugitive pigment.

Certain aspects provide for a method of producing a liquidfire-retardant concentrate. In certain aspects, the method comprisesmixing a premix component comprising a fugitive color system disclosedherein and/or the dry-powder component disclosed herein with a liquidfire-retardant component. In certain aspects, the liquid fire-retardantcomponent is selected from the group consisting of an ammonium phosphatesolution, an ammonium sulfate solution, an ammonium thiosulfatesolution, and mixtures thereof. In certain aspects, the liquidfire-retardant component is an ammonium phosphate solution such as10-34-0 or 11-37-0. In certain aspects, the premix further comprises oneor more of a suspending clay, a corrosion inhibiting system, and/or abiopolymer.

Certain aspects provide for a method of producing a fire-retardantsolution. In certain aspects, the method comprises diluting a liquidfire-retardant concentrate disclosed herein with water. In certainaspects, the liquid fire-retardant concentrate is diluted with water atthe concentrate:water ratio required to provide minimum acceptablefire-retardation performance as defined by U.S.D.A. Forest ServiceSpecification 5100-304c. Certain aspects provide for a fire-retardantsolution, wherein the solution is produced by diluting a liquidfire-retardant concentrate disclosed herein with water. In certainaspects, a fire-retardant solution comprises a liquid fire-retardantconcentrate disclosed herein diluted in water. In certain aspects of afire-retardant solution, the fugitive pigment of the fugitive colorsystem and/or dry powder component of the fire-retardant concentrate iscapable of stabilizing the solution. In certain aspects, the fugitivepigment of the fugitive color system and/or dry powder component of thefire-retardant concentrate stabilizes the solution. In certain aspects,the fire-retardant solution is more stable than a control fire-retardantsolution that is identical in composition except for not containing afugitive pigment exhibiting hydrophilic behavior and/or a hydrophilicfugitive pigment.

Also provided for herein is a method of preparing a fire retardantcomposition adapted for aerial application to wildland fuels andwildland fires, the method comprising the steps of: (a) forming anintermediate storage-stable liquid concentrate composition comprising atleast (i) a liquid fire retardant comprised of at least one ammoniumpolyphosphate, (ii) a fugitive pigment exhibiting hydrophilic behaviorand/or that is a hydrophilic fugitive pigment, (iii) and optionallyother functional components, (b) dilution of the liquid composition withwater to form a fire-retardant solution exhibiting a minimum standard offire-retardantcy, (c) applying the fire-retardant solution on wildlandfuels threatened by fire or (d) on the periphery of the fuel:fireinterface, resulting in a reduction in fire intensity.

Also provided for herein is a storage-stable liquid fire-retardantsolution obtained by diluting any one of the liquid fire-retardantconcentrates as described herein with water at a ratio of 5.5 volumes ofwater per 1.0 volume of the liquid fire-retardant concentrate.

Certain aspects provide for a fugitive color system comprising afugitive pigment and a water insoluble opaque material, wherein thefugitive pigment comprises a dye encapsulated within a polymericmaterial and wherein the fugitive pigment is a fugitive pigment asdescribed anywhere herein and has a surface free energy of about orgreater than about 33, 35, 40, 45, 48.8, 50, 55, 58.8, 60, 70, 80, 85,or 90 mN/m, or any range in between.

A fugitive color system comprising a fugitive pigment and a waterinsoluble opaque material, wherein the fugitive pigment comprises a dyeencapsulated within a polymeric material and wherein the fugitivepigment is a fugitive pigment as described anywhere herein and has apolar component value of about or greater than about 5, 6, 7, 8, 10, 12,15, 20, 20.9, 25, 26.5, 30, 40, 50, or any range in between.

BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES

FIG. 1 shows the stability of liquid retardant concentrates (stored at120° F./49° C.).

FIG. 2 shows the viscosity variability within Concentrate 1 after 7 daysof storage.

FIG. 3 shows the viscosity variability within Concentrate 2 after 7 daysof storage.

FIG. 4 shows the stability of Concentrates 1 and 2, after 7 days ofstorage as measured by turbidity method.

FIG. 5 shows the stability of Concentrates 1 and 2, after 7 days ofstorage as measured by gravimetric method.

FIG. 6 shows the stability of Concentrates 1 and 2, after 14 days ofstorage as measured by gravimetric method.

FIG. 7 pictorially shows the stability of fire-retardant solutionsprepared with Concentrate 1 (left) and Concentrate 2 (right).

DETAILED DESCRIPTION Definitions

To the extent necessary to provide descriptive support, the subjectmatter and/or text of the appended claims is incorporated herein byreference in their entirety.

It will be understood by all readers of this written description thatthe exemplary aspects and embodiments described and claimed herein maybe suitably practiced in the absence of any recited feature, element orstep that is, or is not, specifically disclosed herein.

It is to be noted that the term “a” or “an” entity refers to one or moreof that entity; for example, “a pigment,” is understood to represent oneor more pigments. As such, the terms “a” (or “an”), “one or more,” and“at least one” can be used interchangeably herein.

Furthermore, “and/or” where used herein is to be taken as specificdisclosure of each of the specified features or components with orwithout the other. Thus, the term and/or” as used in a phrase such as “Aand/or B” herein is intended to include “A and B,” “A or B,” “A”(alone), and “B” (alone). Likewise, the term “and/or” as used in aphrase such as “A, B, and/or C” is intended to encompass each of thefollowing embodiments: A, B, and C; A, B, or C; A or C; A or B; B or C;A and C; A and B; B and C; A (alone); B (alone); and C (alone).

It is understood that wherever aspects are described herein with thelanguage “comprising,” otherwise analogous aspects described in terms of“consisting of” and/or “consisting essentially of” are also provided.

Unless defined otherwise, technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this disclosure is related. Numeric ranges areinclusive of the numbers defining the range. Even when not explicitlyidentified by “and any range in between,” or the like, where a list ofvalues is recited, e.g., 1, 2, 3, or 4, unless otherwise stated, thedisclosure specifically includes any range in between the values, e.g.,1 to 3, 1 to 4, 2 to 4, etc.

The headings provided herein are solely for ease of reference and arenot limitations of the various aspects or aspects of the disclosure,which can be had by reference to the specification as a whole.

For purposes of this disclosure, a “fugitive color” is as defined inSection 6 of U.S.D.A. Forest Service specification 5100-304c, June 2007,as follows: “A coloring agent that imparts a high degree of visibilityto the mixed product when first applied to wildland fuels but willgradually disappear over several months.” In certain aspects, the dyecolor intensity is negatively impacted by the ultraviolet intensity ofnatural sunshine.

As used herein, a “dye” is a coloring material used in solution forstaining other materials and a “pigment” is a colored solid powder thatis mixed with other materials to alter their color.

As used herein, a “finely divided” material means that ≥99.5% ofparticle sizes are <44 microns, as determined per the art establishedstandard ISO 787-7, which is incorporated herein by reference in itsentirety. For example, a finely divided pigment grade red iron oxidegenerally falls within the range of 1 to 5 microns.

As used herein, “particle density” is the volumetric mass of the solidand differs from “apparent density” because the volume used does notcontain pores or spaces. This value can be obtained by placing a knownweight of powder in a liquid and measuring the volume displacement witha graduated cylinder.

As used herein “apparent bulk density” is the mass of a sample takenwithout compaction divided by volume as measured using the artestablished ASTM D6683-01, which is incorporated herein by reference inits entirety.

As used herein, “oil absorption”—expressed in X g/100 g of pigment—isthe amount of oil (X g) it takes to turn 100 g of pigment into a pasteof smooth consistency as measured using the art established standard ISO787-5, which is incorporated herein by reference in its entirety.

As used herein, “mean particle size” is the average particle sizediameter as measured using a LS 13 320 instrument that uses laserdiffraction methods as described in the art established standard ISO13320-1, which is incorporated herein by reference in its entirety.

This disclosure relates to fugitive color systems and storage-stablefugitive colored liquid long-term fire retardant compositions comprisinga fugitive color system. The fugitive color system comprises a fugitivecolor pigment. In particular, disclosed herein is the identification offugitive color pigments exhibiting hydrophilic or diminished hydrophobictendencies. And, in certain aspects, the fugitive color pigment isfluorescent. Further, in certain aspects, the combination of ahydrophilic fugitive colorant system of this disclosure is significantlyeasier to wet, incorporate, disperse, and/or homogenize within aqueouslong-term wildland fire retardant concentrates, both during manufactureand during subsequent static storage. Also, in certain aspects, a liquidfire-retardant concentrate containing the fugitive colorant systemexhibits improved storage stability, for example, both in terms of thelength of time before the initiation of separation and sedimentation andthe rate of separation during long term static storage. For example, incertain aspects, such improved storage stability is observed even at themaximum expected 120° F. (49° C.) elevated temperature experienced insummer time fire-prone areas. Stable concentrate suspensions maintain ahomogeneous system of the functional components in a concentratedliquid, minimizing the need for continual reconstitution. Lastly, whenseparation does ultimately occur during prolonged storage of thefugitive colored liquid fire retardant concentrate, it is easilyobservable because the colorant pigment and other insoluble componentssettle from the top of the concentrate, leaving behind an obvioustransparent layer rather than simultaneously rising within theconcentrate mass and settling from the center of the liquid concentratecolumn where it cannot be seen as is experienced with previous fugitivecolored long-term retardant concentrates.

Certain aspects of the present invention involve improved storagestability as determined by monitoring an increase in turbidity ofdiluted samples of a liquid fire-retardant concentrate of the presentinvention. For example, liquid fire-retardant concentrates of thepresent invention have been observed to exhibit substantially constantstability as indicated by an increase in Nephelometric Turbidibity Units(NTU) of no more than about 25%, no more than about 20%, no more thanabout 15%, or no more than about 12% for a plurality of dilutedconcentrate samples tested after storage for 7 days. Similarly, liquidfire-retardant concentrates of the present invention have been observedto exhibit substantially constant storage stability as indicated by astandard deviation of Nephelometric Turbidibity Units (NTU) of less thanabout 25%, less than about 20%, less than about 12% for a plurality ofdiluted concentrate samples tested after storage for 7 days. Liquidfire-retardant concentrates of the present invention typically alsoexhibit improved storage stability for up to 14 days (or even longer) asindicated by visual observation and/or by satisfying one or more of thecriteria listed above.

Fugitive Color System

Provided herein is a fugitive color system comprising a fugitive pigmentand a water insoluble opaque material. The fugitive pigment comprises adye encapsulated within a polymeric material. One purpose forencapsulating the dye within the polymer material is so that the dyedoes not stain the people, equipment, etc. with which it comes intocontact. In certain aspects, the polymeric material can be, for example,petroleum resins (CAS #64742-16-1), melamine (CAS #108-78-1), and thelike as known to one of ordinary skill in the art. In certain aspects,the dye is a fluorescent dye. In certain aspects, the dye and thepolymer work together to achieve fluorescence, e.g., the dye and resincombination comprising the fugitive pigment fluoresces. Unlike fugitivepigments presently used in fugitive color systems for fire retardants,the fugitive pigment of this disclosure exhibits hydrophilic or reducedhydrophobic behavior in comparison to the currently utilized fugitivepigments. In certain aspects, the fugitive pigment is hydrophilic. Incertain aspects, the fugitive pigment is easy to incorporate into anaqueous media. In certain aspects, the fugitive pigment more easilyincorporates into an aqueous media in comparison to a control fugitivepigment that does not exhibit hydrophilic behavior and/or is nothydrophilic. For example, the fugitive pigment may be a hydrophobiccontrol fugitive pigment containing Solvent Red 1 dye CAS #1229-55-6,two hydrocarbon resins CAS #64742-16-1 and CAS #64742-94-5, and TiO₂ CAS#13463-67-7 opacifier, in the amounts of 80-88% resin, 7-10% dye, and5-10% TiO₂ opacifier. Distinguishing characteristics of currently usedfugitive color systems, in comparison to the fugitive color system ofthis disclosure, are that currently used fugitive color systems are notfluorescent, they do not contribute to concentrate stability duringstatic storage, they are marginal in visibility when freshly applied,and they do not result in retardant solutions that maintain homogeneityduring static storage.

An opaque material is one that is neither transparent nor translucentand by “water insoluble,” it is meant that the water solubility is ≤5%as determined by the art established standard ISO 787-3, which isincorporated herein by reference in its entirety. In certain aspects,the water insoluble opaque material comprises a finely divided ironoxide pigment, zinc ferrite, tri-calcium phosphate, barium phosphate, ortitanium dioxide. In certain aspects, the water insoluble opaquematerial comprises a finely divided iron oxide pigment. In certainaspects, the opacifier is in a minor amount. In certain aspects, theopacifier is in an amount of about 0.1% to about 0.8% (wt/wt). Incertain aspects, the fugitive colored liquid long-term fire retardantexhibits a hue optically visible to the human eye when applied asrelatively thin (⅛^(th) inch thick) films on the trees, brush, grasses,and mixtures thereof, that are encountered in wildland and other underdeveloped fire-prone rural areas.

In certain aspects, a fugitive pigment of this disclosure exhibitinghydrophilic behavior and/or a fugitive pigment that is hydrophilic is afluorescent fugitive pigment. Representative fluorescent pigments usefulin this disclosure are, for example, described in U.S. Pat. No.5,439,968 “Fluorescent Pigment Concentrates,” which is incorporatedherein by reference in its entirety.

Further in accordance with the present invention, in certain aspects thefugitive pigment is formaldehyde-free. This feature provides an improvedfugitive pigment where the presence of formaldehyde is undesired. It isto be understood that a formaldehyde-free fugitive pigment in accordancewith the present invention may be combined with any or all of the othercomponents listed herein and/or may be utilized in compositions (e.g., afugitive color system or liquid fire-retardant concentrate) defined byany or all of the properties listed herein.

In certain aspects, the fugitive pigment or dye is magenta. In certainaspects, the fugitive pigment or dye is a fluorescent magenta in color.In certain aspects, the fluorescent pigment or dye has a Lab colorspacing of “L” in a range from about 34 to about 89, “a” in a range fromabout 18 to about 83, and “b” in a range from about −61 to about 56. Itwas observed that a magenta fluorescent fugitive pigment was an optimumcolorant based on its visibility within the many colors found inwildland brush, timber, trees, grasses, etc. However, one of ordinaryskill in the art will recognize that the fugitive pigments of thisdisclosure are not limited to magenta or fluorescent magenta.

In certain aspects, a fluorescent fugitive pigment is any one of the ECOPigments manufactured by DayGlo Corporation. In certain aspects, thefluorescent fugitive pigment is ECO-20, Ultra Violet manufactured byDayGlo Corporation. In certain aspects, the fluorescent fugitive pigmentis ECO-21, Corona Magenta manufactured by DayGlo Corporation (1-5 weight% C.I. Basic Violet 11, CAS-No. 2390-63-8 and 1-5 weight % C.I. BasicRed 1:1, CAS-No. 3068-39-1; melting/freezing point 145° C.-150° C.;specific gravity 1.2). In certain aspects, the fluorescent fugitivepigment is ECO-15, Blaze Orange manufactured by DayGlo Corporation. Incertain aspects, the fluorescent fugitive pigment is ECO-14, Fire Orangemanufactured by DayGlo Corporation. In certain aspects, the fluorescentfugitive pigment is ECO-13, Rocket Red manufactured by DayGloCorporation. In certain aspects, the fluorescent fugitive pigment isECO-11, Aurora Pink manufactured by DayGlo Corporation. In certainaspects, the fluorescent fugitive pigment is ECO-21, Corona Magentamanufactured by DayGlo Corporation. In certain aspects, the fluorescentfugitive pigment is Magenta 108PB distributed by Royale Pigments &Chemicals (Appendix A).

It has been discovered that in certain aspects, the fugitive pigments ofthe fugitive color system of this disclosure share in common possessionof at least one of the following properties:

(i) a 0.5% (w/w) suspension of the fluorescent fugitive pigment indistilled H₂O has a pH of about pH 4 to pH 7 (about pH 5.6 in certainaspects);

(ii) the fugitive pigment has a softening point of ≥60° C. (about 134°C. in certain aspects);

(iii) the fugitive pigment has a melting range of ≥130° C. (about 145°C. to about 150° C. in certain aspects);

(iv) the fugitive pigment has a particle density of about 1.2 g/ml toabout 1.5 g/ml (about 1.2 g/ml in certain aspects);

(v) the fugitive pigment has an apparent bulk density of about 0.25 g/mlto about 0.37 g/ml (about 0.37 g/ml in certain aspects);

(vi) the fugitive pigment exhibits oil absorption of about 55 g/100 g toabout 80 g/100 g (about 80 g/100 g pigment in certain aspects); and

(vii) the fugitive pigment has a mean particle size of about 4.5 μm toabout 5.0 μm.

In certain aspects, a fugitive pigment of the disclosure possess, one ormore, two or more, three or more, four or more, five or more, or six ormore of the above properties. In certain aspects, a fugitive pigment ofthe disclosure possesses, one, two, three, four, five, six, or all sevenof the above properties.

Liquid fire-retardant concentrates comprise a dry-powder componentincorporated within an aqueous component. In certain aspects, thedry-powder component of a fugitive colored liquid long-term fireretardant of this disclosure comprises a fugitive color system and oneor more of: a suspending agent; a biopolymer (such as xanthan, rhamsanor welan); an opacifier; and corrosion inhibitors (for example, thoseselected to inhibit corrosion of aluminum, steel, brass and sometimesmagnesium). In certain aspects, the dry powder component can alsocontain surfactants, de-foamers, anti-foamers, and other functionalcomponents.

A dry powder's ability to wet is related to its surface free energymilliNewton per meter (mN/m) as determined in all values disclosedherein via the Washburn method, using a K100 force tensiometer andSH0820 sample holder. The Washburn method is a method for measuring thecontact angle and the surface free energy of porous substances such asbulk powder or pigments, and absorbent materials such as paper ortextiles (Washburn, E. W., Phys. Rev. 17, 374 (1921)). In arepresentative example of a Washburn measurement, a glass tube with afilter base filled with powder comes into contact with a test liquid.The liquid is drawn up as a result of capillary action. The increase inmass of the tube, which is suspended from a force sensor, is determinedwith respect to time during the measurement. If the bulk powder islooked upon as a bundle of capillaries, then the process can bedescribed by the Washburn equation:

$\frac{m^{2}}{t} = \frac{{c \cdot \rho^{2} \cdot \sigma \cdot \cos}\;\theta}{\eta}$(m=Mass; t=Flow time; σ=Surface tension of the liquid; c=Capillaryconstant of the powder; ρ=Density of the liquid; θ=Contact angle;η=Viscosity of the liquid)

The constant c includes the number of micro-capillaries and their meanradius, and depends on the nature of the powder and also on that of themeasuring tube. Plotting the square of the mass m² against time t showsa linear region, the slope of which, for known liquid properties (σ, ρand η), only contains the two unknowns c and θ. To determine theconstant c, a measurement is carried out with an optimally wetting(spreading) liquid (e.g. n-hexane), with which the contact angle θ is 0°(cos θ=1). The value of c is substituted in the equation in order todetermine the contact angle θ with the help of other liquids. Thecontact angle measured in this way is an advancing angle, as it ismeasured in the course of wetting. The surface free energy of the powdercan be calculated from the contact angle data with the help of differentmodels. As c depends on the bulk density, it should be ensured that thepowder is packed consistently for all measurements on the same powder.

The rule of thumb is that the surface free energy of the powder has tobe higher than the surface tension of the liquid for spontaneous wettingto occur. That is, the higher the surface free energy of the dry powder,the more easily it is wetted. Liquid ammonium phosphate has a surfacetension of about 90 mN/m. It was observed that a dry-powder formulationcontaining a conventional fugitive pigment had a surface free energy ofabout 32.0 mN/m. In contrast, the same dry-powder formulation containinga fugitive color system of the present disclosure had a surface freeenergy greater than 32 mN/m. In certain aspects of this disclosure, adry-powder formulation for use in a liquid fire-retardant concentratehas a surface free energy greater than 32 mN/m. In certain aspects, adry-powder formulation for use in a liquid fire-retardant concentratehas a surface free energy of about 33, 35, 40, 45, 48.8, 50, 55, 58.8,60, 65, 70, 75, 80, 85, or 90 mN/m, or any range in between. In certainaspects, a dry-powder formulation for use in a liquid fire-retardantconcentrate has a surface free energy of greater than about 33, 35, 40,45, 48.8, 50, 55, 58.8, 60, 65, 70, 75, 80, 85, or 90 mN/m. Anothercharacteristic that can distinguish powders is the “polar component”value (also determined via the Washburn method, using a K100 forcetensiometer and SH0820 sample holder). The higher the polar componentvalue, the better the wetting behavior the powder has with polarsolvents. It was observed that a dry-powder formulation containing aconventional fugitive pigment had a polar component of 4.1. In contrast,the same dry-powder formulation containing a fugitive color system ofthe present disclosure had a polar component significantly greater than4.0. In certain aspects, a dry-powder formulation for use in a liquidfire-retardant concentrate has a polar component value of about 5, 6, 7,8, 10, 12, 15, 20, 20.9, 25, 26.5, 30, 35, 40, 45, 50 or any range inbetween. In certain aspects, a dry-powder formulation for use in aliquid fire-retardant concentrate has a polar component of greater thanabout 5, 6, 6, 7, 8, 10, 12, 15, 20, 20.9, 25, 26.5, 30, 35, 40, 45, or50. In certain aspects, a dry-powder formulation with the above definedcharacteristics comprises any fugitive color system as descriedelsewhere herein.

In certain aspects of this disclosure, a dry-powder formulation for usein a liquid fire-retardant concentrate is synonymous with a fugitivepigment. Thus, in certain aspects, a fugitive pigment of this disclosurehas a surface free energy greater than 32 mN/m. In certain aspects, afugitive pigment has a surface free energy of about 33, 35, 40, 45,48.8, 50, 55, 58.8, 60, 65, 70, 75, 80, 85, or 90 mN/m, or any range inbetween. In certain aspects, a fugitive pigment has a surface freeenergy of greater than about 33, 35, 40, 45, 48.8, 50, 55, 58.8, 60, 65,70, 75, 80, 85, or 90 mN/m. In certain aspects, a fugitive pigment has apolar component value of about 5, 6, 7, 8, 10, 12, 15, 20, 20.9, 25,26.5, 30, 35, 40, 45, 50 or any range in between. In certain aspects, afugitive pigment has a polar component of greater than about 5, 6, 6, 7,8, 10, 12, 15, 20, 20.9, 25, 26.5, 30, 35, 40, 45, or 50.

In accordance with the foregoing, in certain embodiments, the presentinvention defines a fugitive color system for use in a fire retardantwith the fugitive color system comprising a fugitive pigment and a waterinsoluble opaque material. The fugitive pigment (e.g., generallycomprising a dye and encapsulated within a polymeric material) ischaracterized by a surface free energy of at least about 45 mN/m and apolar component value of at least about 20 mN/m. Such a fugitive colorsystem may be defined by any or all of the above-listed properties.Advantageously in accordance with the present invention, the colorsystem incorporates a formaldehyde-free fugitive pigment.

The present invention is also directed to dry-powder formulations (e.g.,a particulate fugitive pigment) exhibiting various advantageousproperties. For example, the particulate fugitive pigment may exhibit amean particle of at least about 4.0 μm, at least about 4.5 μm, or fromabout 4.0 to about 5.0 μm. In certain aspects, such fugitive pigmentsare formaldehyde-free and/or defined by one or more of the propertiesnoted elsewhere herein (e.g., surface free energy and/or polar componentvalue).

Liquid Fire-Retardant Concentrate

Provided for herein is a liquid fire-retardant concentrate comprising afugitive color system and/or dry-powder component (which comprises afugitive color system) as disclosed herein, suspended in a liquidfire-retardant component. In certain aspects, the fugitive pigment ofthe fugitive color system and/or dry powder component is fluorescent. Incertain aspects, the fugitive color system and/or fugitive pigment ofthe color system is capable of stabilizing the fire-retardantconcentrate. As used herein, “stabilizing,” “stabilizes,” and the likerefers to the stabilization of the composition of the insolublecomponents within the liquid component of the concentrate (asexemplified in the Examples which follow). In certain aspects, thefugitive color system and/or fugitive pigment of the color systemstabilizes the fire-retardant concentrate. In certain aspects, theliquid fire-retardant concentrate also comprises one or more of: asuspending clay, a corrosion inhibiting system, or a biopolymer,suspended in the liquid fire-retardant component. In certain aspects,the fugitive color system is in an amount of about 1.0% to about 1.5%(w/w) of the fire-retardant concentrate. For example, in an amount ofabout 0.9%, 1.0%, 1.2%, 1.3%, 1.4%, 1.5%, or 1.6% (w/w) of thefire-retardant concentrate. In certain aspects, the liquidfire-retardant component is selected from the group consisting of anammonium phosphate solution, and ammonium sulfate solution, an ammoniumthiosulfate solutions, and mixtures thereof. For example, in certainaspects, the liquid fire-retardant component is an ammonium phosphatesolution. In certain aspects, the liquid fire-retardant concentratecomprises a fugitive color system as disclosed herein, a suspendingclay, a corrosion inhibiting system, and a biopolymer, all of which aresuspended in the liquid fire-retardant component.

In certain aspects, the liquid ammonium polyphosphate component isselected from agricultural liquid fertilizer solutions containing about10 to 11% ammonia, about 34 to 37% phosphorus pentoxide, and 0%potassium oxide. These solutions are generally referred to in the fieldas either 10-34-0 or 11-37-0 liquid concentrates. In certain aspects,the ammonium phosphate component is a 10-34-0 agricultural liquidfertilizer solution. In certain aspects, the ammonium phosphatecomponent is an 11-37-0 agricultural liquid fertilizer solution. In somecases, during the manufacture of the fertilizer solutions, anhydrousammonia is added to orthophosphoric acid in an enclosed pipe reactor.When the anhydrous ammonia reacts with the phosphoric acid in anenclosed area, both pressure and temperature increase resulting in theformation of condensed ammonium phosphates, i.e., ammoniumpyrophosphates, short chain length ammonium polyphosphates, perhaps someammonium metaphosphates, and other longer chain species. Generally, 10to 20% of the phosphoric acid remains as monoammonium orthophosphateand/or diammonium orthophosphate in freshly manufactured 11-37-0,although the amount of orthophosphate in the liquid solution increasesduring storage via hydrolyses of the polymers and a decrease in theamount of the condensed phosphates. After aging for several months inambient temperatures, the amount of orthophosphate can be equal to ormore than the amount of condensed ammonium phosphates. While in certainaspects, 10-34-0 and 11-37-0 are chosen because they are readilycommercially available, it should be recognized that similar solutionswith higher or lower levels of ammonia and phosphorus pentoxide can alsobe used as the liquid component. In certain aspects, ammonium sulfatesolutions can also be substituted for ammonium phosphate solutions whenformulating long-term fire retardants. Although Forest ServiceSpecifications currently require the use of only ammonium phosphatebased fire retardant in products meeting the requirements of FederalGovernment Agencies, it should be recognized that other liquid fireretardants could be used, for example: ammonium sulfate solutions orammonium thiosulfate solutions.

Further in accordance with the present invention, the fire retardantcomponent of concentrates of the present invention may include acombination of monoammonium phosphate (MAP) and diammonium phosphate(DAP). Typically in accordance such concentrates a suspending agent(e.g., micronized clay) is further included). In accordance with thepresent invention, the fire-retardant concentrates can be prepared usingtechnical grade MAP and DAP which lack detectable levels of sulfate,thus providing a “sulfate-free” composition. In other instances, theconcentrates can be prepared using fertilizer grade MAP and DAP whichcan contain low levels of sulfates. When prepared using fertilizer gradeMAP and DAP, the amount of sulfate in the liquid concentrate may be lessthan the detectable amount in an equivalent composition prepared usingammonium polyphosphate. Thus, the amount of sulfate in the liquidconcentrate can constitute less than about 2%, less than about 1%, orless than about 0.5% by total weight of the composition. In someembodiments, the concentrates comprise less than about 1.5%, less thanabout 1.4%, less than about 1.3%, less than about 1.2%, less than about1.1%, or less than about 1% detectable sulfates by weight of thecomposition.

Generally, any of the liquid fire-retardants utilized in theconcentrates of the present invention can comprise at least one ammoniumphosphate. In certain embodiments, the ammonium phosphate comprises,consists essentially of, or consists of monoammonium phosphate (MAP). Inother embodiments, the ammonium phosphate comprises, consistsessentially of, or consists of diammonium phosphate (DAP). In someembodiments, the liquid fire retardant concentrate compositions providedherein comprise a mixture of ammonium phosphates. In certainembodiments, the ammonium phosphate or mixture of ammonium phosphateshas a molar ratio of ammoniacal nitrogen to phosphorus (N/P ratio) in arange from about 1.1 to about 1.9. In certain embodiments, the ammoniumphosphate or mixture of ammonium phosphates has a molar ratio ofammoniacal nitrogen to phosphorus (N/P ratio) in a range from about 1.35to about 1.65. In certain embodiments, the ammonium phosphate or mixtureof ammonium phosphates has a molar ratio of ammoniacal nitrogen tophosphorus (N/P ratio) in a range from about 1.4 to about 1.6. Incertain embodiments, the ammonium phosphate or mixture of ammoniumphosphates has a molar ratio of ammoniacal nitrogen to phosphorus (N/Pratio) in a range from any of about 1.1, 1.2, 1.3, 1.35, 1.4, 1.5, 1.6,1.7, or 1.8 to any of about 1.2, 1.3, 1.4, 1.5, 1.6, 1.65, 1.7, 1.8, or1.9. The concentrate and its solutions generally contain less ammonia incomparison with previous products, and can result for example, in alower aquatic toxicity.

The mixture of ammonium phosphates can comprise at least two ammoniumphosphates. In certain embodiments, the mixture of ammonium phosphatescomprises, consists essentially of, or consists of monoammoniumphosphate (MAP) and diammonium phosphate (DAP). In certain embodiments,the MAP contains from about 10% or 11% to about 12% ammonia by weightand from about 40% or 55% to about 61% phosphorus pentoxide by weight.In certain embodiments, the DAP contains from about 16% to about 21%ammonia by weight and from about 40% to about 54% phosphorus pentoxideby weight. Further, in certain embodiments, the weight ratio of MAP toDAP is in the range of from about 5% to about 60% MAP to about 40% toabout 95% DAP of the total ammonium phosphate in the concentrate. Incertain embodiments, the weight ratio of MAP to DAP is in the range offrom about 40% to about 60% MAP to about 40% to about 60% DAP of thetotal ammonium phosphate in the concentrate. In certain embodiments, theweight ratio of MAP to DAP is in the range of from about 50% to about60% MAP to about 40% to about 50% DAP of the total ammonium phosphate inthe concentrate.

In further embodiments, a fire-retardant concentrate compositioncomprises from about 19% to about 50% by weight of DAP. The compositioncan comprise from about 19% to about 47% by weight of DAP. For example,the composition can comprise from about 20% to 30% of DAP. In someinstances, the composition comprises from about 25% to about 27% byweight of DAP (e.g., about 26%).

In still further embodiments, the fire-retardant concentrate compositioncomprises from about 1% to about 30% of MAP. The composition cancomprise from about 10% to about 30% of MAP. For example, thecomposition can comprise from about 20% to about 30% by weight of MAP.In some instances, the composition comprises from about 22% to about 24%by weight of MAP (e.g., about 23%).

As noted above, in accordance with the present invention variousembodiments incorporate the MAP and DAP within certain preferred ratiosto enhance solubility of the ammonium phosphates. Therefore, in certainembodiments, the weight ratio of MAP to DAP is from about 40:60 to about60:40, or from about 45:55 to about 55:45 (e.g., about 46:54 or about47:53).

Further in accordance with the present invention, the fugitive colorsystems and fugitive pigments of the present invention may beincorporated into and/or combined with liquid fire-retardant concentratecompositions, fire-retardant solutions, etc. as defined in U.S.Provisional Application Ser. No. 62/802,902, filed Feb. 8, 2019(Attorney Docket No. 3514297.0102; PSOL 9098.USP) and U.S. Ser. No.15/670,422 (Attorney Docket No. 3514297.000501; PSOL 9089.US), theentire contents of which are hereby incorporated by reference for allrelevant purposes.

In certain aspects, a liquid fire-retardant concentrate comprising afugitive pigment of this disclosure exhibits compositional stabilitythroughout. In certain aspects, a liquid fire-retardant concentratecomprising a fugitive pigment of this disclosure is more stable than acontrol fire-retardant concentrate that is identical in compositionexcept for not containing the fugitive pigment of this disclosure.

In certain aspects, during manufacture of a long-term liquid fireretardant concentrate, the dry powder components are weighedindividually and blended together to form a premix. Then a specifiedweight, or volume, of liquid ammonium phosphate solution is added to atank fitted with an agitator capable of shearing, stirring andhomogenizing the two components together. Agitation of the concentrateis continued until the two components are thoroughly homogenized. Thatis, in certain aspects, a method of producing a liquid fire-retardantconcentrate comprises mixing a premix component comprising a fugitivecolor system of this disclosure with a liquid fire-retardant component.In certain aspects, the liquid fire-retardant component is any asdisclosed elsewhere herein.

It has been shown that in order to achieve homogeneity; the lengthand/or intensity of agitation may need to be altered dependent on thecharacteristics of the dry powder components in the premix. Thecomposition of a typical liquid fugitive colored long-term fireretardant concentrate is illustrated in Table 1.

TABLE 1 Liquid Long-Term Fugitive Colored Fire Retardant ConcentrateComposition. Composition Amount (weight %) Liquid ammonium phosphatesuch as 93.0 to 95.0 11-37-0 or 10-34-0 Biopolymer, xanthan, rhamsan orwelan 1.0 to 2.0 Clay, attapulgus, kaolin or other 1.0 to 2.0Fluorescent fugitive color pigment 1.0 to 2.0 Red iron oxide 0.1 to 0.8Ferric pyrophosphate 2.0 to 4.0 Azole corrosion inhibitor <1.0

Thus, in certain aspects, the premix further comprises one or more of asuspending clay, a corrosion inhibiting system, and/or a biopolymer. Incertain aspects, one of ordinary skill in the art will understand tovary the weights of the components in order to obtain the requiredconcentration of a critical moiety or the desired physical properties ofthe concentrate or solution. For example, the ammonium polyphosphatereceived from a supplier does not always contain exactly 34.0% or 37.0%phosphorus pentoxide (P₂O₅) that is the critical moiety necessary forfire retardation. In order to correct for this, the amount of ammoniumphosphate solution must be varied to assure that the concentrate and itssolutions have the required amount of this substance and consequentlyalways perform as expected. In certain aspects, the biopolymer has beenshown to function as both a corrosion inhibitor and solution thickener.It can function as a corrosion inhibitor for aluminum alloys in theconcentrate but does not function as a thickener until dilution water isadded to prepare the solution. Consequently, the biopolymerconcentration may need to be varied slightly to obtain the viscosity orto reduce corrosion. In certain aspects, the quantity of clay can alsobe altered to obtain the desired concentrate viscosity. Since all lotsof clay do not possess identical thickening capability, it can benecessary to make slight adjustments in the amount of clay to obtain thedesired concentrate viscosity. In certain aspects, a small amount ofiron oxide is added as an opacifier for the fugitive color pigment andis considered a part of the fugitive color system. In certain aspects,the fugitive color system, for example a fluorescent fugitive colorsystem, is in general transparent. It has been shown that a small amountof iron oxide or other relatively inert, powdered particulates furtheropacifies the pigment and thereby cause a more vivid color to beperceived optically. The quantity of opacifier material is minimized,however, so that it does not significantly impact the faded color of thefugitive color pigment. Agricultural grade ammonium phosphate solutionscan contain a relatively high and varying level of impurities. Thus, incertain aspects, the quantities of ferric phosphate and triazole can bevaried to maintain a low corrosion rate in both the concentrate and itssolution.

Field experimentation was conducted in the search for a more opticallyvisible color pigment for use in long-term, liquid ammonium phosphatefire retardant solutions used in the attack of wildland fires. It wasdetermined that a fluorescent, magenta-colored pigment, that was one ofseveral potential pigments involved in the testing, was considerablymore visible to the human eye than a comparable loading, or even ahigher loading, of the International orange-red pigment that had beenused for more than 30-years and any of the other experimental pigmentsand mixtures thereof.

During subsequent laboratory experimentation, it was observed thatpremixes comprising certain color pigments previously unused infire-retardant solutions wet much easier than expected when added to anagitated aqueous ammonium phosphate concentrate during manufacture and,subsequently, were slower to separate and settle during long termstorage. Thus for purposes of this disclosure and as used herein, theseeasier to wet fugitive pigments are referred to as having hydrophilictendencies, as having reduced hydrophobic tendencies, as hydrophilicpigments, and the like, and prior pigments as hydrophobic pigments. Inview of their organic surfaces, both said hydrophilic pigments and priorhydrophobic pigments can exhibit some degree of hydrophobic tendency.However, the magnitude of the difference between the hydrophilicpigments and the hydrophobic orange-red (non-fluorescent) pigment, interms of the ease of incorporation, dispersion and homogeneity within anaqueous ammonium phosphate solution, the storage stability ofsubsequently prepared solutions and its performance when mixed withaqueous ammonium phosphate solution demonstrate that there is a vastdifference between the two in degree of aversion to water.

Fire-Retardant Solutions

Provided for herein is a method of producing a fire-retardant solutioncomprising diluting a liquid fire-retardant concentrate as disclosedherein with water. Thus, certain aspects provide for a fire-retardantsolution produced by diluting a liquid fire-retardant concentrate asdisclosed herein with water. Certain aspects provide for afire-retardant solution, wherein the solution comprises the liquidfire-retardant concentrate diluted in water. In certain aspects, theliquid fire-retardant concentrate is diluted with water at theconcentrate:water ratio required to provide minimum acceptablefire-retardation performance as defined by U.S.D.A. Forest ServiceSpecification 5100-304c (U.S. Patent Pub. No. 2018/0037998, which isincorporated herein by reference in its entirety).

In certain aspects, the fugitive pigment of the fugitive color system ofthe fire-retardant concentrate is capable of stabilizing the solution.In certain aspects, the fugitive pigment of the fugitive color system ofthe fire-retardant concentrate stabilizes the solution. In certainaspects, the fire-retardant solution comprising the fugitive pigment ismore stable than a control fire-retardant solution that is identical incomposition except for not containing the fugitive pigment.

Further provided herein is a method of preparing a fire retardantcomposition adapted for aerial application to wildland fuels andwildland fires, the method comprising the steps of: (a) forming anintermediate storage-stable liquid concentrate composition comprising atleast (i) a liquid fire retardant comprised of at least one ammoniumpolyphosphate, (ii) a fugitive pigment of this disclosure, (iii) andoptionally other functional components, (b) dilution of the liquidcomposition with water to form a fire-retardant solution exhibiting aminimum standard of fire-retardantcy, (c) applying the fire-retardantsolution on wildland fuels threatened by fire or (d) on the periphery ofthe fuel:fire interface, resulting in a reduction in fire intensity.

Also disclosed herein is a storage-stable liquid fire-retardant solutionobtained by diluting any one of the liquid fire-retardant concentratesof this disclosure with water at a ratio of 5.5 volumes of water per 1.0volume of the liquid fire retardant concentrate.

In certain aspects, when using a liquid fire-retardant concentrate ofthe type described in U.S. Pat. Nos. 6,780,991B2 and 6,828,437B2 (bothincorporated herein by reference in their entireties), one volume of theconcentrate is blended with 5.5 volumes of potable water to yield about6.5 volumes of retardant solution. The U. S. Forest Service determinesthe prescribed dilution rate during their testing as described in thepreviously mentioned Federal Specification. This rate is based on thelevel of fire retarding salt or moiety present in the concentrate. Thefire retardant capability of ammonium phosphate solution is dependent onthe available phosphorus pentoxide (P₂O₅) content of the fire retardantconcentrate. If the solution or concentrate is not homogeneous at thetime it is withdrawn from storage, the resultant fire retardant solutionmay not perform as expected resulting in property loss and perhapsdeath.

In certain aspects, the liquid retardant concentrate is stored in one ormore tanks in the out-of-doors (typically ranging in capacity of from3,000 to 25,000 gallons, or possibly higher up to, for example, 80,000gallons) at an airport, or other fire Agency facility, ready forimmediate use when a fire emergency occurs. In certain aspects, liquidlong-term fire retardant concentrates are also stored in 1000-literportable totes in situations where permanent storage tanks are notavailable. In certain aspects, these tanks and totes contain no internalmixing or stirring equipment although they are generally capable ofrecirculation via pumping accessories. The length of concentrate storagecan range from a few minutes from receipt to, perhaps a year, two years,three years, or more. Because in certain aspects, the tanks areout-of-doors and unheated or cooled, the temperature of the solution canvary from below zero during winter months to 100° F. or more during thefire-prone summer months. (Forest Service Specification 5100-304crequires that retardant concentrates and their diluted solutions providean effective amount of corrosion protection at 120° F. so this isgenerally accepted as the expected maximum storage temperature).

EXAMPLES Example 1

Concentrate Stability Determined by Visual Observation:

Long-term liquid fire retardant concentrates were prepared within thecompositional parameters described in Table 1. Two Concentrates wereprepared. The first (1) contained a control, standard orange-red,non-fluorescent hydrophobic pigment and the other (2) contained amagenta colored, fluorescent, hydrophilic fugitive pigment. Table 2below illustrates certain properties of the two pigments.

The Concentrates were prepared identically as herein described. The drypowder premix components were weighed individually and then blendedtogether to form a homogeneous powder. Simultaneously, thepre-determined amount of ammonium polyphosphate solution (11-37-0) wasadded to a stainless steel mixing vessel fitted with a baffle and alaboratory stirrer adjusted to a rotational speed of 1200 rpm. The drypowder premix was then slowly added into the center of the agitatedliquid. When necessary a spatula was used to scrape dry or partiallywetted powder from the container walls and the agitator shaft. When allof the powder was incorporated into the liquid, agitation was increasedto 3500 rpm and continued for 20 minutes. It was noted that Pigment 1was more difficult to wet, requiring considerable manual cleaning inorder to obtain complete incorporation of the semi-wetted pigment intothe liquid phase. The semi-wetted pigment rises to the surface of theagitated mixture acting as a hydrophobe. At the end of mixing,Concentrate 1 had a viscosity of 210 cPs when measured with a BrookfieldModel LVT viscometer fitted with Spindle 2 rotating at 60 rpm.Concentrate 1 exhibited a Specific Gravity (SpG) of 1.454 grams percubic centimeter at 70° F./21° C. Under the same conditions, Concentrate2 exhibited a viscosity of 201 cPs and a SG of 1.456. Three887-milliliter samples of each concentrate were prepared.

TABLE 2 Characteristics of Fugitive Color Pigments Fugitive ColorPigment Orange-red Magenta Non-fluorescent (1) Fluorescent (2)Hydrophobic Hydrophilic Pigment Pigment Color Int'l Orange-Red MagentaEase of dispersion in water Hydrophobic Hydrophilic Fluorescent No YesStability - presence UV light Fades Fades Water solubility insolubleInsoluble pH - 0.5% sol'n in dist. H₂O 6.2 5.6 Softening Point - ° F./°C. 265-285/130-140 57/134 Melting Range - ° F./° C. — 284-302/145-150Particle Density - g/ml 1.25 1.2 Apparent Bulk Density - g/ml 0.35  0.37Oil Absorption - g/100 g 55 80   pigment Mean Particle Size -μm 1.2-1.54.5-5.0 Formaldehyde present No No

TABLE 3 Composition of Long-Term Liquid Fire Retardant Concentrates. RawMaterial Concentrate 1 Concentrate 2 11-37-0 Ammonium phosphate (%) 94.092.7 Biopolymer 1.1 1.1 Micronized clay 1.4 1.4 Int'l orange-redfugitive pigment (1) 1.0 New Magenta fugitive pigment (2) 1.5 Opacifier(%) 0.3 0.1 Azole corrosion inhibitor 0.2 0.2 Iron pyrophosphate 2.0 3.0

Three 800 milliliter samples of each concentrate were transferred intowide-mouth, screw cap, one-quart glass containers for static storage.About one-hour after preparation, the top of Concentrate 1 appeared tohave partially dried with a dull matte appearance whereas the top ofConcentrate 2 appeared to be a homogeneous, wet suspension with a glossycolor. Each container was closed during storage. Previous experiencewith fire retardant concentrates, revealed that separation andsedimentation occurs most rapidly when stored at elevated temperatures.Consequently, samples stored at elevated temperature received greaterscrutiny and separation was confirmed to appear more rapidly at higherambient storage temperatures. The concentrates were frequently observedvisually for signs of separation and sedimentation. FIG. 1 illustratesthe observed separation during 30-days of static storage at atemperature of 120° F./49° C. It also demonstrates the degree of storagestability variability that is experienced when the same formulation,manufacturing procedure and storage conditions are repeated intriplicate.

FIG. 1 shows that separation of Concentrate 1 began four days afterstorage was initiated. In this sample, between 16 and 24% of the sampleheight at the bottom of the container was a clear green solution, thecolor of the ammonium polyphosphate component. Thus, it appeared thatthe insoluble particulates rise from the center of the container towardthe upper surface of the container. Such a result would be difficult toobserve in field use when the container is a large, metal tankcontaining several thousand gallons of Concentrate. The solids continuedto separate, rising to the point where 25 to 40% of the total volume wasclear liquid after 30-days storage.

In contrast, Concentrate 2 exhibited no separation until day eleven andthen only 2% separation appearing as clear greenish liquid on the topsurface of the liquid where it was clearly visible to the operator. Thelevel of separation subsequently increased to about 5% after 18-days andthen remained stable through 30-days. This example demonstrates that,visually, Concentrate 2 appeared to be considerably more stable thanConcentrate 1 and, when using Concentrate 2, the operator can clearlyobserve the degree of separation and the success of reconstitution viarecirculation.

Example 2

Ease of Concentrate Incorporation and Dispersion:

Several experiments were conducted to assess differences in the ease ofwetting and dispersing the premix of dry powdered components within theaqueous liquid phase of the formulation. In these experiments, thecomposition and conditions of preparing the Concentrates were heldconstant in all cases. The composition of the Concentrate is the same asthe Concentrate in Table 3. Four different fugitive pigments wereevaluated, i.e., two each meeting the herein definition “(orange-red,non-fluorescent) hydrophobic pigment” and “(magenta, fluorescent),hydrophilic pigment”.

a. Incorporation of Premix Component within Liquid Phase:

1128-grams of aqueous 11-37-0 ammonium phosphate solution was placed ina 1-liter beaker containing a baffle and a motor driven 2-inch Cowlesturbine blade for agitation. With the beaker in place, the agitatormotor was adjusted to 1200-rpm. At this speed, there was rapid turnoverof the liquid but a vortex was not present. A homogeneous premix of thedry-powder component was prepared separately. This premix was added tothe rapidly sheared liquid phase; the premix was added quickly in orderto start recording the time necessary to achieve incorporation of thepowders within the liquid. A micro spatula was used to scrape dry powderoff of the beaker sides, baffle and stirrer shaft moving it into theagitated 200-cP Concentrates. The amount of required manual assistancewith the spatula varied with the hydrophobic nature of the fugitivepigment used in the premix. The timer was stopped when all of the premixpowders were incorporated within the liquid. Total incorporation of thedry powders within the liquid does not mean that the powders werehomogeneously dispersed, only that they were not present on the liquidsurface during agitation.

TABLE 4 Time to Incorporate Premix in Liquid Phase. Pigment used informulation Time to Incorporate (min) Hydrophilic Magenta A 2:75Hydrophilic Magenta B 3:00 Hydrophobic Orange-red A 5:00 HydrophobicOrange-red B 4:50

While the differences in time to achieve incorporation of the dry powderis not large, the amount of manual manipulation required to keep thepowder from clinging to the beaker sides and the stirrer shaft wassignificant and not possible in a large scale operation. Also, thedegree of dispersion of the powder throughout the liquid phase is, atthis point, unknown.

b. Dispersion of Premix Component within Liquid Phase:

Following incorporation of the dry-powder premix within the liquidphase, the Cowles turbine agitator was paused for 1-minute whileobservations were made. When agitation was resumed, the rotational speedwas increased to 2100-rpm and continued for 2-minutes. A vortexdeveloped when the speed of agitation was increased. Agitation was againpaused for 1-minute to make observations and then continued at the samespeed for an additional 5-minutes. Again there was a 1-minute pausewhile observations were made. When agitation was resumed, the rotationalspeed was increased to 3500-rpm, near the maximum possible withoutsplashing liquid from the beaker. After 2-minutes at 3500-rpm, stirringwas discontinued and final observations made. The observations are asfollow:

i. Concentrates containing orange-red non-fluorescent pigment basedPremixes: At the end of the incorporation Stage, the surface ofConcentrate 1 was covered with a matte consisting of what appeared to besemi-wetted globules of powdered materials. After the first 2-minutes ofmixing, at 2100-rpm, the semi-wetted globules continued to appearalthough the rate of rising to the surface and the size of the globulescan have decreased somewhat. At the end of an additional 5-minutesmixing at 2100-rpm, little change was noted in either size or rate ofsurfacing. A considerable improvement was noted after mixing fortwo-minutes at 3500-rpm, although smaller semi wetted globules werestill apparent and a matte slowly surfaced when agitation wasdiscontinued.

ii. Concentrates containing magenta fluorescent pigment based Premixes:At the end of the incorporation Stage of mixing, the surface of theConcentrate was covered with semi-wetted globules of powder that slowlyappeared on the surface after agitation was stopped. The size and numberof globules were considerably less than with Concentrate 1. There was asignificant decrease in both the rate of surfacing and the size of theglobules after mixing for an additional 5-minutes at 2100-rpm. Aftermixing for 2-minutes at 3500-rpm, no globules were observed on theConcentrate surface and it was glossy.

c. Examination of Concentrate Homogeneity:

After the mixing tests were completed, the consistency of the fourpremixes was examined by drawing down a film on glass and noting thedegree of smoothness and the presence of agglomerates and globules. Asample of each Premix was drawn down on a smooth transparent glass plateusing a 0.064 inch stepped edge doctor blade. The films of thoseConcentrates containing the magenta colored fluorescent fugitive pigmenthad a high gloss and appeared uniform with no sign of globules oragglomerates. The films of those Concentrates containing the orange redcolored non-fluorescent fugitive pigments had a dull color and areaswith an opaque/matte appearance indicating that they continued tocontain semi-wetted particulates.

Example 3

Viscosity Uniformity within Concentrate Following Storage:

It is important that the liquid concentrate be homogeneous in order forthe proper amount of each ingredient in the concentrate to be presentwhen discharged from the storage tank, and diluted during transfer tothe delivery vehicle. For example, if the color is not present in theprescribed amount, it will not be possible to distinguish between thevegetative fuel that has been covered with sufficient fire retardantsolution to resist burn-through when the wildfire arrives at theretardant-covered fire line. Likewise, if the thickener is either absentor present in excess, the aerial application of the liquid fireretardant will not be optimum, i.e., improper length and width and rateof application. It is, of course, necessary that the other functionalcomponents, such as the corrosion inhibitors, be present in theprescribed quantity as well.

While Example 1 illustrated the visual difference between Concentrates 1and 2, that data was based on observations obtained by visually lookingat the outer edge of the cylindrical container and assuming that theinterior of the solution is similar to that visible from the outside.Example 3, on the other hand, illustrates the impact of storage on theviscosity of the diluted concentrate present at eight levels rangingfrom the bottom to the top of the cylinder of liquid Concentrate.

Two 6800-ml samples of each Concentrate 1 and 2 were prepared inaccordance with the composition illustrated in Table 1. They wereprepared in a 19-liter round container fitted with a baffle attached toone side and using a motor driven 4-inch Cowles turbine blade foragitation. The agitator motor was adjusted to 1250-rpm. The dry powdercomponents were added through the course of one minute. After thesecomponents had been added, the mixer speed was increased to 1500 rpm forthe next 20-minutes. The mixer speed was then increased to 1800 rpm for10 minutes before turning off. Two aliquots obtained from eachconcentrate was transferred to the same type of 800-ml glass containerdescribed in Example 1. In this case, however, the side of the glasscontainer was previously measured and marked at each inch starting fromthe bottom. The height of the solution in the container was 8-inches,thus the marks on the outside of the glass represented 100-milliliterportions of the total. The bottom 100-ml of solution was labeled 1. Thenext 100-ml was labeled 2 and so forth until the top 100-ml aliquot waslabeled 8. The four Concentrate samples were then placed in staticstorage at 49° C./120° F.

After seven days of static storage, one of the two samples of eachConcentrate was removed and divided into eight 100-ml aliquots viasyringe starting at the top of the Concentrate sample. This aliquot wasplaced in a 600-ml beaker. This sequence was continued until all eightportions of the storage sample were retrieved. By continual removal ofthe top portion, those portions that remained in the storage containerremained undisturbed until its time of retrieval. After removal of theeight portions from one 800-ml sample of Concentrate 1, the portionswere individually homogenized and 60-ml aliquots, from the 100-mlportion, was diluted with 330-ml of tap water. This is equivalent to theprescribed 5.5:1 by volume dilution of the concentrates determinedduring qualification of the formulation by the U.S. Forest Service pertheir Specification 5100-304c.

The second storage sample of each 800-ml Concentrate was removed fromstorage and immediately homogenized by mixing at 2100-rpm with apropeller stirrer for 5-minutes. After being homogenized, the secondstorage sample was divided into 8-aliquots in the same manner as that ofthe first storage sample. Following retrieval, 60-ml of these eightaliquots were mixed with 330-ml of tap water using a 2-inch propellerblade for 5-minutes at 2100-rpm. This resulted in 16-samplesrepresenting portions of each Concentrate after 7-days of staticstorage; 8 of each Concentrate were removed prior to reconstitution andeight representing portions of a previously homogenized solution.

FIG. 2 illustrates the variability of the solution viscosity within the800-ml sample of Concentrate 1 after 7-days of static storage at 120°F./49° C. It is assumed that variability in solution viscosity isdirectly proportional to the variability of the biopolymer content ofeach portion of the complete sample. These data show that Concentrate 1had separated into aliquots ranging in viscosity from 125 to 210 cPprior to reconstitution. The second set of data in FIG. 2 illustratesthe viscosity and variability that exists after the Concentrate wasre-homogenized, i.e., viscosity varied from 178 to 188 cPs which isprobably well within the reproducibility of the viscometer used.Scrutiny of the data shows that the bottom half of the solution containsless thickener than it should and it appears to be floating upwardwithin the solution. This is consistent with the visual observations inExample 1.

Two 800-ml samples of Concentrate 2 were stored and sampled in the samemanner as described for Concentrate 1. FIG. 3 illustrates the viscosityvariability experienced when Concentrate 2 was stored for 7 days underthe same conditions as Concentrate 1. The Concentrate was then treatedin the same homogenizing and sampling manner as Concentrate 1. Theviscosity was measured as described above for Concentrate 1. The resultsof this study are illustrated in FIG. 3.

The data illustrated in FIG. 3 shows that the viscosity of Concentrate 2after 7-days of static storage at 120° F./49° C. was essentiallyidentical to the viscosity of the reconstituted sample showing that nochange (separating, settling or deteriorating) in the thickeningcomponent had occurred during 7-days of static storage. One canspeculate that if the thickener remains suspended homogeneously withinthe solution, then the other insoluble components will be as well.

Example 4

Particulate Dispersion within the Fire Retardant Concentrate:

The thickener, fugitive color pigment, opacifier and many of thecorrosion inhibitors are insoluble in the liquid phase of the long-termliquid fire retardant concentrate. It is desirous to maintain ahomogeneous mix of the two phases during storage. Thus, it is possibleto illustrate stability of the concentrate during storage by determiningthe turbidity of fractional samples taken from a stored mass. Todemonstrate this, an 800-ml sample of each, Concentrate 1 andConcentrate 2, were prepared and stored under static conditions for7-days and handled as described in paragraphs 2 and 3 of Example 3. Theeight aliquots of each Concentrate were then inverted twenty times tore-suspend any potential sediment at the bottom of the container. Then0.7812-ml of each aliquot was transferred to a 50-ml polypropylenecentrifuge tube using a 1-ml Eppendorf pipette and diluted with DI waterto 50-ml (1:64 dilution). The diluted sample was then mixed well byinverting and shaking and then transferred to a turbidity-measuringvial. The turbidity of each sample was determined with a HACH 2100ANNephelometric Turbidity Units (NTU) meter with all settings in default.The results are illustrated in Table 5 and FIG. 4.

TABLE 5 Turbidity of Cross-sectional Samples of Concentrates 1 and 2Aliquot Concentrate 1 Concentrate 2 bottom 1 1207 1491 2 1334 1343 3 7391303 middle 4 734 1435 5 1680 1594 6 1690 1523 7 1755 1534 top 8 18201593

These data illustrate that after 7-days of static storage at atemperature of 120° F./49° C. Concentrate 2 is more uniform, in terms ofturbidity caused by suspended solids, than Concentrate 1. The standarddeviation of the NTU turbidity units for Concentrate 2 is 109 or 7.4% ofthe average level of turbidity whereas Concentrate 1 exhibits a standarddeviation of 444 or 32.4% of the average NTU value. This standarddeviation is a measure of the scatter of particles within the one-eighthgradient samples.

Scrutiny of FIG. 4 shows that Concentrate 1 is separating with suspendedparticulate matter rising within the liquid phase from the lower middleof the sample column toward the top where visual observation (seeExample 1) reported that a matte of material formed on the surface ofthe solution. These data do not indicate that sediment separated to thebottom of the container in this first week of storage.

In a second study, Concentrates 1 and 2 were stored for 14-days prior tosampling and testing as described in the previous paragraph. The datacollected from this study revealed that the particulates present inConcentrate 1 continued to rise toward the surface during the secondweek of storage; rising from the center of the column of Concentratetoward the surface with the increase of particulate appearing as athicker matte at the surface. There was, also, an indication of somesettling to the bottom of the container/tank as well. This indicatesthat there is a particulate heavy layer at the bottom of the tank, asecond layer representing approximately 35% of the total that containsless than the required quantity of insolubles with a heavy matte ofparticulate floating in the top. Meanwhile Concentrate 2 continued toexhibit little change with all of the particulates within an NTU rangeof 1000 to 1400.

The dispersion of particulate material within the liquid phase of thetwo Concentrates following static storage was also determinedgravimetrically. This data further confirms the information gleaned fromthe visual, viscosity and turbidity measurements. In this case eightcross-sectional aliquots were removed from 800-ml samples that had beenstored as described above. These aliquots were inverted twenty times tore-suspend any potential sediment. Then 15-grams of each aliquot of thetwo Concentrates was transferred to pre-labeled and pre-weighedcentrifuge tubes and centrifuged at 16,000-rpm for 30-minutes. Thesupernatant was then carefully decanted and the tubes inverted on athick stack of absorbent paper toweling for 2-hours to completely removeany remaining liquid. The tubes containing the particulates were thenplaced within a chemical hood and allowed to air-dry overnight. Thecentrifuge tubes containing the particulates were then weighed and thenet weight of particulates in each of the tubes calculated. FIG. 5illustrates the weight of particulates present in each of the aliquots.

Separate 800-ml samples were prepared and stored under static conditionsfor 14-days before the eight aliquots were withdrawn in the same manneras described above for the 7-day storage period. These aliquots wereinverted to re-suspend sediment, transferred to pre-weighed and labeledcentrifuge tubes, centrifuged at 16,000-rpm for 30-minutes, supernatantdecanted, dried and weighed. The weight of particulates in each aliquotis illustrated in FIG. 6.

Comparison of FIG. 5 and FIG. 6 indicates that the rate of separation ofConcentrate 1, which contains the non-fluorescent, hydrophobic fugitivepigment, is accelerating, i.e., the amount of separation that occurredbetween 7-days and 14-days is considerably greater than that whichoccurred during the first 7-days of storage. The curves also indicatethat separation within Concentrate 1 is proceeding via particulatesettling and moving toward the upper surface of the liquid column.Meanwhile, Concentrate 2, containing the hydrophilic fugitive pigment,remains stable.

Example 5

Storage Stability of Long-Term Fire Retardant Solution.

As described previously, long-term fire retardants composed of ammoniumphosphate solutions rather than dry powders are stored as an aqueousliquid concentrate that is mixed with water at the time of use. Theaqueous liquid concentrates consist of particulate ingredients suspendedhomogeneously within a liquid phase. Previous examples described thestability of these liquid fire retardant concentrates during staticstorage awaiting dilution at the time of use. When the call for help isreceived, the liquid fire retardant Concentrate is diluted with potablewater. The liquid fire retardant Concentrates described in Table 2 werequalified for use when 1 part by volume of the Concentrate is dilutedwith 5.5 parts by volume water to form an approximately 20% by weightsolution of the concentrate.

The storage stability of fire retardant solutions prepared by admixing1-part by volume of Concentrates 1 and 2 with 5.5 parts by volume ofpotable water and storing them at 70° F./21° C. for several months on alaboratory bench is illustrated in the photographs in FIG. 7. Thesebottles of diluted solution were not prepared for laboratory study andwere consequently not monitored during storage. They have, in fact, beenshaken on an unknown number of occasions to illustrate the consistencyof the two solutions. Neither bottle was, however, disturbed for severaldays prior to the time this picture was taken. The solution containingdiluted Concentrate 1, consisting of a non-fluorescent, hydrophobicfugitive pigment, is on the left while the solution of the right wasprepared with Concentrate 2 containing the fugitive pigment and ironoxide opacifier. The composition of both Concentrates can be found inTable 2.

Example 6

U.S. Pat. No. 5,439,968 provides for a low plate-out fluorescent pigmentconcentrate comprising: (a) a pigment comprising a polyamide and afluorescent dye and (b) a carboxylated polyolefin consisting essentiallyof polyethylene or polypropylene having a molecular weight of about1,000 to about 100,000, the polyolefin containing pendant acid oranhydride residue groups in the amount of about 0.25% to about 10% byweight based on the weight of the polyolefin, and the polyolefin beingpresent in sufficient amount to disperse the pigment. The polyamide ormodified polyamide which is used in the fluorescent pigment can be anyof the conventional thermoplastic polymers having a melting point of60°-200° C. Polyamides are well known in the art, and are the reactionproducts of dicarboxylic acids or amino acids and diamines. Typicaldicarboxylic acids are those having 6 to 12 carbon atoms. Typicaldiamines are those having 6 to 12 carbon atoms. The acid or diamine canbe substituted with conventional substituents such as, for example,alkyl from one to 12 carbons. Typical polyamides include nylon 6, nylon66, nylon 610 and nylon 11. “Polyamide” is intended to include suchsubstituted polyamides. The polymeramide can have a molecular weight of500 to 100,000. Conventional, well-known processes are used in preparingthe polyamides.

The fluorescent pigment can be present in an amount of about 5 to about50 wt %, e.g., about 20 to about 40 wt %, based upon the total weight ofthe concentrate. They must also be sufficiently heat stable.Combinations of two or more fluorescent pigments can be used.

Fluorescent pigments are also referred to as daylight fluorescentcolors. Daylight fluorescent colors with few exceptions are really nottrue pigments but are instead solid solutions of fluorescent dyes intransparent synthetic resins which are finely ground to a particle sizein the range of 2 to 5 microns.

The fluorescent pigments can be said to be fluorescent dyes in molecularsolution in the carrier resin. Examples of fluorescent dyes useful inpreparing the fluorescent pigments are the fluorescent brightenerscontaining sulfo groups, in particular stilbene fluorescent brighteners,especially those of the type of the bis-triazinylaminostilbenedisulfonicacids, the bis-styrylbiphenyls, the bis-styrylbenzenes and thebis-triazolylstilbenedisulfonic acids. The fluorescent brightenerscontaining sulfonic acid groups can be in the form of their metal salts,for example, lithium, potassium, magnesium or sodium salts, and alsoammonium, amine or alkanolamine salts. Fluorescent brightener compoundswhich have been partially acidified or fluorescent brighteners in theform of the free acid can be used. Any of the fluorescent brightenerscontaining sulfo groups of U.S. Pat. No. 4,466,900 can be used, which isincorporated herein by reference in its entirety.

Other examples of fluorescent dyes which can be used to prepare thefluorescent pigments are the fluorescent naphthalimide dyes for example,Morton Fluorescent Yellow G (Color Index 75), Fluorol 7GA (ColorIndex-Fluorescent brightening agent 75), Calcofluor Yellow (ColorIndex-Fluorescent brightening agent No. 4) and Azosol Brilliant Yellow 6GF (Color Index-Solvent Yellow 44), and the fluorescent cuomarin dyes,for example, Calcofluor White RW (Color Index fluorescent brighteningagent 68) and Blancophor White AW (Color Index-Fluorescent brighteningagent 68). Other useful fluorescent dyes include Rhodanine B, Rhodanine6 GDN, Auramine, Eosine G, Calcofluor White ST, Pontamine White RT,Pontamine White BTS, Rhodamine Bx, Phthalocyamine, Alkali Blue G,Phthalocyamine, Rhoamine 7G, Rhodamine FB, Rhodamine S, Rhodamine 5G,Bright Yellow 3G, Tetramethyl Rhodamine, Rhodamine FG, Rhodamine F4G,Fanal Pink D, Fanal Violet D, Flexo Yellow 110, Lumogen Yellow D,Fluorol Green Gold, Fluorol Yellow and Thermoplast F-Orange.

Certain representative examples of fluorescent pigments are those basedon polyamides from Day-Glo Color Company.

The fluorescent pigments can be prepared with the aid of dyeingassistants.

In contrast to normal pigments, the fastness to light of fluorescentpigments is only moderate. This is a result of the poor light fastnessof the fluorescent colorants they contain; the carrier resins themselvesbeing very stable to light. The addition of UV stabilizers, e.g.,benzophenone and benzotriazole classes, gives marked improvements. Suchproducts are frequently already present in the fluorescent pigments.

Many of the commercially available fluorescent pigments recommended forplastics are heat-stable only up to moderate temperatures because of thelimited thermal stability of the carrier resins. These temperatures forshort dwell times range between 180° C. and 230° C. according to thetype of carrier resin and its degree of 60 cross-linking. Processingtemperatures in such range suffice for the final plastic products wherethey are molded at a temperature of up to 425° F., e.g., 400° F. (about205° C.) or less.

The fluorescent pigments must not be subjected to too high of shear inthe dry blending operation as it may adversely affect the colorcharacteristics of the fluorescent pigments.

Useful homo or copolymers of α-olefins include low molecular weightpolyethylene, crystalline polypropylene, amorphous polypropylene,mixtures of crystalline and amorphous polypropylene, poly-1-butene, andpropylene copolymers with one or more higher α-olefins. Useful higherα-olefins include 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene,1-decene, and 4-methyl-1-pentene.

The α-olefins are reacted using conventional techniques with at leastone unsaturated acid or anhydride having 3 to 5 carbon atoms or a 1-10carbon atom ester thereof. Representative acids, anhydride, or estersinclude maleic anhydride, dimethyl maleate, acrylic acid, methacrylicacid, and crotonic acid.

Certain polyolefins containing pendant acid or anhydride residue groupsare polyethylene and polypropylene containing pendant maleic anhydrideresidue groups.

A process for preparing the low plate-out fluorescent pigmentconcentrate involves: (I) dry blending the pigment and polyolefin, forexample using high intensity mixing conditions, but not subjecting thepigment particle surfaces to such high shear so as to materially affectthe color characteristics of the pigment particles; and (II) melt mixingthe dry blended mixture at a temperature of 425° F. or lower andoptionally forming the melt mixed material into a form useful forfabrication. In certain aspects the forming of the melt-mixed materialinvolves the steps of: (a) forming the melt-mixed materials intostrands; (b) cooling the strands; and (c) pelletizing the strands. Thetemperature during extrusion should not exceed 425° F.

In formulating the concentrate the ingredients are for example in powderform and are in dry form. The fluorescent pigment concentrates aredispersed in polymers in order to form molded articles containingfluorescent pigments. Any conventional dispersion or incorporationmeans, such as, a mixer, can be used. The dispersions of polymer andfluorescent pigment concentrate are molded, using any conventionalmolder, into molded articles.

Generally, sufficient concentrate should be used to provide aconcentration of from about 0.10 to about 2 wt % (based on the totalweight of the final plastic product) of fluorescent pigment in the finalplastic product.

The compositions used to form the final polymer products can contain theusual additives, such as, heat and/or light stabilizers. Some materialwhich act as lubricants can adversely affect the plate-outcharacteristics.

Example Basis Formulation

Polyolefin Resin 0-46% Fluorescent Pigment  35% Filler (equal to or less 10% than two microns average particle size) TiO₂    2% Silcron G-100   2% Wax Dispersant 5-51% Note: Inorganic material like barium sulfateor various clays.

Mixing Procedure

1. Weigh-out ingredients into high-intensity mixer

2. Mix on medium speed for 1 minute

3. Discharge material

Extrusion Procedure:

1. Set temperatures no higher than 425° F.

2. Extrude into strands

3. Run strands through water bath to cool

4. Run cooled strands through a pelletizer

Plate-Out Test:

1. Place 5.0 g of concentrate onto polished press plates

2. Put plates into press set at no more than 375° F.

3. Apply enough pressure to get a press-out of about 20 mils

4. Remove plates and cool in water bath

5. Remove pressed material and visually evaluate residue deposited ontoplate

6. Rating system:

-   -   (a) Excellent (no plate-out)    -   (b) Good (very little plate-out)    -   (c) Moderate plate-out    -   (d) Bad plate-out    -   (e) Very bad plate-out

The concentrates rating as OK in this work are rated no higher than atwo. A rating of 3 is marginal, and ratings of 4 and 5 are considered tobe unacceptable. All others are considered to have too much plate-out.

The present disclosure is not to be limited in scope by the specificaspects described or preceding Examples which are intended as singleillustrations of individual aspects of the disclosure, and anycompositions or methods which are functionally equivalent are within thescope of this disclosure. Indeed, various modifications of thedisclosure in addition to those shown and described herein will becomeapparent to those skilled in the art from the foregoing description andaccompanying drawings. Such modifications are intended to fall withinthe scope of the appended claims.

All publications and patent applications mentioned in this specificationare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

APPENDIX A Royale Pigments & Chemicals Magenta 108 PB Chemical nameCommon name and synonyms CAS # COMPOSITION Isophorone diamine3-Aminomethyl-3,5,5-trimethyl 2855-13-2 Cyclohexylamine IPD Petroleumresins 64742-16-1 1,3-Benzenedicarboxylic acid Isophthalic acid 121-91-5Benzoic acid Benzenecarboxylic acid 65-85-0l,3,5-Triazine-2,4,6-triamine Melamine 108-78-1 Isobutanolamine2-Amino-2-methyl-1-propanol 124-68-5 Calcium carbonate Aragonite471-34-1 Calcium monocarbonate Polyphosphoric acids, Ammoniumpolyphosphate 68333-79-9 ammonium salts Xanthylium, 3,6-bis(ethylamino)-CI Basic Red 1:1 3068-39-1 9-[2-(methoxycarbonyl)phenyl]- 2,7-dimethyl-,chloride Xanthylium,3,6-bis(diethylamino)- CI Basic Violet 11:173398-89-7 9-[2-(methoxycarbonyl)phenyl]-, (T-4)-tetrachlorozincate(2-)(2:1) 2-Naphthalenol, CI Solvent Red 1 1229-55-61-[(2-methoxyphenyl)azo]- PHYSICAL AND CHEMICAL PROPERTIES pH 6.5-7.5Melting/Freezing Point 165-175° C. Bulk Density (gms/cc) 0.25-0.35Particle size in Microns D 50 3-4 (Wet method - by D 90 8-10 MalvernMastersizer 3000) D 100 14-18

What is claimed is:
 1. A liquid fire-retardant concentrate, theconcentrate comprising a liquid fire-retardant component and aninsoluble phase comprising a fugitive color system, the fugitive colorsystem comprising a fugitive pigment and a water insoluble opaquematerial, wherein: the fugitive pigment is formaldehyde-free andcomprises a fluorescent dye encapsulated within a polymeric material andis characterized by a surface free energy of at least about 45 and apolar component value of at least about 20; and the liquidfire-retardant concentrate exhibits a substantially constant storagestability for at least 7 days.
 2. The liquid fire-retardant concentrateof claim 1 wherein the substantially constant storage stability isexhibited under static storage conditions and at a temperature of up to120° F./49° C.
 3. The liquid fire-retardant concentrate of claim 1wherein the substantially constant stability is indicated by an increasein Nephelometric Turbidibity Units (NTU) of no more than about 25%, fora plurality of diluted concentrate samples tested after storage for 7days.
 4. The liquid fire-retardant concentrate of claim 1 wherein thesubstantially constant storage stability of the concentrate is indicatedby a standard deviation of Nephelometric Turbidibity Units (NTU) of lessthan about 25%, for a plurality of diluted concentrate samples testedafter storage for 7 days.
 5. The liquid fire-retardant concentrate ofclaim 1 wherein the liquid fire-retardant concentrate exhibits asubstantially constant storage stability for 14 days.
 6. The liquidfire-retardant concentrate of claim 5 wherein the substantially constantstability is indicated by an increase in Nephelometric Turbidibity Units(NTU) of no more than about 25%, for a plurality of diluted concentratesamples tested after storage for 14 days.
 7. The liquid fire-retardantconcentrate of claim 5 wherein the substantially constant storagestability of the concentrate is indicated by a standard deviation ofNephelometric Turbidibity Units (NTU) of less than about 25%, for aplurality of diluted concentrate samples tested after storage for 14days.
 8. The liquid fire-retardant concentrate of claim 1 wherein thefugitive pigment is fluorescent.
 9. The liquid fire-retardantconcentrate of claim 1 wherein the liquid fire-retardant component isselected from the group consisting of an ammonium phosphate solution, anammonium sulfate solution, an ammonium thiosulfate solution, andmixtures thereof.
 10. The liquid fire-retardant concentrate of claim 9wherein the liquid fire-retardant component is an ammonium phosphatesolution.
 11. The liquid fire-retardant concentrate of claim 9 whereinthe liquid fire-retardant component is a 10-34-0 agricultural fertilizersolution.
 12. The liquid fire-retardant concentrate of claim 9 whereinthe liquid fire-retardant component is an 11-37-0 agriculturalfertilizer solution.
 13. The liquid fire-retardant concentrate of claim9 wherein the liquid fire-retardant component comprises a mixture ofmonoammonium phosphate (MAP) and diammonium phosphate (DAP).
 14. Theliquid fire-retardant concentrate of claim 1 wherein the concentratefurther comprises one or more components selected from the groupconsisting of a suspending clay, a corrosion inhibiting agent, abiopolymer, and mixtures thereof.
 15. A fire-retardant solution, thefire-retardant solution comprising the liquid fire-retardant concentrateof claim 1 and water.
 16. A method for preparing a fire-retardantsolution, the method comprising diluting the liquid fire-retardantconcentrate of claim 1 with water.